fix: move scroll lock to afterUpdate to avoid SSR document access

The $: reactive block runs during SSR component init. Use afterUpdate
with a mounted guard instead so document is only accessed client-side.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

opal-web/src/lib/components/BottomSheet.svelte

@@ -1,6 +1,5 @@
 <script>
-	import { onMount, onDestroy } from 'svelte';
-	import { browser } from '$app/environment';
+	import { onMount, onDestroy, afterUpdate } from 'svelte';
 
 	/** @type {boolean} */
 	export let open = false;
@@ -11,6 +10,7 @@
 	let dragOffset = 0;
 	let dragging = false;
 	let locked = false;
+	let mounted = false;
 
 	/** @type {number|null} */
 	let startY = null;
@@ -29,8 +29,9 @@
 	/** @type {HTMLDivElement|null} */
 	let sheetEl = null;
 
-	// Body scroll lock
-	$: if (browser) {
+	// Body scroll lock — managed in afterUpdate to avoid SSR document access
+	afterUpdate(() => {
+		if (!mounted) return;
 		if (open) {
 			document.documentElement.style.overflow = 'hidden';
 		} else {
@@ -39,7 +40,7 @@
 			dragging = false;
 			locked = false;
 		}
-	}
+	});
 
 	/**
 	 * @param {KeyboardEvent} e
@@ -69,6 +70,7 @@
 	}
 
 	onMount(() => {
+		mounted = true;
 		document.addEventListener('keydown', handleKeydown);
 	});